This section provides background information related to the present disclosure which is not necessarily prior art.
Air induction systems are used in motor vehicles and for other applications to transport air from the environment to an engine for combustion. As air moves through the air induction system and into the engine, noise and vibration from the engine may be transmitted and amplified by the passages forming the air induction system. In order to reduce the volume or amplitude of air pulsations that may particularly correspond to the opening and closing of engine air intake valves and other characteristics of these noises, it may be desirable to utilize a resonator that is configured to resonate at and reflect sound waves at one or more frequencies related to the undesirable noise so as to modify the sound characteristics of the air induction system. In this manner, sound waves may be produced that attenuate or reduce the sound waves produced by the engine.
In some situations, it may be desirable to provide a resonator that effectively responds to more than one sound wave, including the frequency thereof, produced by the engine. For example, when the engine is running at low RPM, it may be desirable to have a low frequency resonator to effectively suppress, or in some cases enhance the amplitude of low frequency sound waves produced by the engine. When the engine is running at high RPM, it may be desirable to have a high frequency resonator to effectively suppress the sound waves produced by the engine. It is known that some frequencies may be experienced as more unpleasant to the human hearing, while other frequencies, in some cases lower frequencies, may enhance the experience of engine power and performance.
Different types of resonators have been used for automotive and related applications. According to one known type of acoustic resonator, a tube in communication with an engine may extend into an air filter box housing. In certain known arrangements, multiple necks originating from separate ports on a clean side duct may terminate at corresponding chambers within a resonator housing. The sound produced by the engine may also be attenuated by adjusting a neck area of the tube.
While known resonators have generally proven to be acceptable for their intended purposes, a continued need in the relevant art remains. In this regard, packaging considerations may restrict the application of conventional manners of sound attenuation.